Set all vector elements to NA in a list of vectors












6














How can I set all vector elements to NA in a list of vectors?



Essentially, I'd like to keep an existing list's structure and names but empty all values, to fill them in later. I provide a minimal example with a couple solutions below. I prefer base and tidyverse (esp. purrr) solutions, but can get on board with any approach which is better than what I have below.



my_list <- list(A = c('a' = 1, 'b' = 2, 'c' = 3), B = c('x' = 10, 'y' = 20))
ret_list <- my_list

# Approach 1
for (element_name in names(my_list)) {
ret_list[[element_name]] <- NA
}

ret_list
# $A
# a b c
# NA NA NA
#
# $B
# x y
# NA NA

# Approach 2
lapply(my_list, function(x) {x <- NA; return(x)})
# $A
# a b c
# NA NA NA
#
# $B
# x y
# NA NA









share|improve this question




















  • 1




    both approaches seem fine to me (especially if you define the function in Approach 2 beforehand rather than anonymously inline). Why try to be cleverer than that? What specific shortcomings would you like to remedy?
    – Ben Bolker
    Dec 31 '18 at 23:27








  • 1




    Just taking an opportunity to understand R a little better. It seemed to me that this was such a common operation that there had to be a standard, best-practices approach.
    – lowndrul
    Dec 31 '18 at 23:40
















6














How can I set all vector elements to NA in a list of vectors?



Essentially, I'd like to keep an existing list's structure and names but empty all values, to fill them in later. I provide a minimal example with a couple solutions below. I prefer base and tidyverse (esp. purrr) solutions, but can get on board with any approach which is better than what I have below.



my_list <- list(A = c('a' = 1, 'b' = 2, 'c' = 3), B = c('x' = 10, 'y' = 20))
ret_list <- my_list

# Approach 1
for (element_name in names(my_list)) {
ret_list[[element_name]] <- NA
}

ret_list
# $A
# a b c
# NA NA NA
#
# $B
# x y
# NA NA

# Approach 2
lapply(my_list, function(x) {x <- NA; return(x)})
# $A
# a b c
# NA NA NA
#
# $B
# x y
# NA NA









share|improve this question




















  • 1




    both approaches seem fine to me (especially if you define the function in Approach 2 beforehand rather than anonymously inline). Why try to be cleverer than that? What specific shortcomings would you like to remedy?
    – Ben Bolker
    Dec 31 '18 at 23:27








  • 1




    Just taking an opportunity to understand R a little better. It seemed to me that this was such a common operation that there had to be a standard, best-practices approach.
    – lowndrul
    Dec 31 '18 at 23:40














6












6








6


1





How can I set all vector elements to NA in a list of vectors?



Essentially, I'd like to keep an existing list's structure and names but empty all values, to fill them in later. I provide a minimal example with a couple solutions below. I prefer base and tidyverse (esp. purrr) solutions, but can get on board with any approach which is better than what I have below.



my_list <- list(A = c('a' = 1, 'b' = 2, 'c' = 3), B = c('x' = 10, 'y' = 20))
ret_list <- my_list

# Approach 1
for (element_name in names(my_list)) {
ret_list[[element_name]] <- NA
}

ret_list
# $A
# a b c
# NA NA NA
#
# $B
# x y
# NA NA

# Approach 2
lapply(my_list, function(x) {x <- NA; return(x)})
# $A
# a b c
# NA NA NA
#
# $B
# x y
# NA NA









share|improve this question















How can I set all vector elements to NA in a list of vectors?



Essentially, I'd like to keep an existing list's structure and names but empty all values, to fill them in later. I provide a minimal example with a couple solutions below. I prefer base and tidyverse (esp. purrr) solutions, but can get on board with any approach which is better than what I have below.



my_list <- list(A = c('a' = 1, 'b' = 2, 'c' = 3), B = c('x' = 10, 'y' = 20))
ret_list <- my_list

# Approach 1
for (element_name in names(my_list)) {
ret_list[[element_name]] <- NA
}

ret_list
# $A
# a b c
# NA NA NA
#
# $B
# x y
# NA NA

# Approach 2
lapply(my_list, function(x) {x <- NA; return(x)})
# $A
# a b c
# NA NA NA
#
# $B
# x y
# NA NA






r






share|improve this question















share|improve this question













share|improve this question




share|improve this question








edited Jan 1 at 0:02

























asked Dec 31 '18 at 22:56









lowndrul

1,16521835




1,16521835








  • 1




    both approaches seem fine to me (especially if you define the function in Approach 2 beforehand rather than anonymously inline). Why try to be cleverer than that? What specific shortcomings would you like to remedy?
    – Ben Bolker
    Dec 31 '18 at 23:27








  • 1




    Just taking an opportunity to understand R a little better. It seemed to me that this was such a common operation that there had to be a standard, best-practices approach.
    – lowndrul
    Dec 31 '18 at 23:40














  • 1




    both approaches seem fine to me (especially if you define the function in Approach 2 beforehand rather than anonymously inline). Why try to be cleverer than that? What specific shortcomings would you like to remedy?
    – Ben Bolker
    Dec 31 '18 at 23:27








  • 1




    Just taking an opportunity to understand R a little better. It seemed to me that this was such a common operation that there had to be a standard, best-practices approach.
    – lowndrul
    Dec 31 '18 at 23:40








1




1




both approaches seem fine to me (especially if you define the function in Approach 2 beforehand rather than anonymously inline). Why try to be cleverer than that? What specific shortcomings would you like to remedy?
– Ben Bolker
Dec 31 '18 at 23:27






both approaches seem fine to me (especially if you define the function in Approach 2 beforehand rather than anonymously inline). Why try to be cleverer than that? What specific shortcomings would you like to remedy?
– Ben Bolker
Dec 31 '18 at 23:27






1




1




Just taking an opportunity to understand R a little better. It seemed to me that this was such a common operation that there had to be a standard, best-practices approach.
– lowndrul
Dec 31 '18 at 23:40




Just taking an opportunity to understand R a little better. It seemed to me that this was such a common operation that there had to be a standard, best-practices approach.
– lowndrul
Dec 31 '18 at 23:40












5 Answers
5






active

oldest

votes


















8














Here's another one for numeric vectors:



lapply(my_list, `*`, NA) # Instead of * it could also be +, -, etc.
# $A
# a b c
# NA NA NA
#
# $B
# x y
# NA NA


More generally,



lapply(my_list, replace, TRUE, NA)


and



lapply(ret_list, ifelse, NA, NA)





share|improve this answer























  • what is * called as in this context ?
    – YOLO
    Dec 31 '18 at 23:12






  • 1




    @YOLO, I'm not sure what you mean. The first approach is the same as lapply(my_list, function(x) x * NA), so * is the usual product, which results to NA when one of the factors is NA.
    – Julius Vainora
    Dec 31 '18 at 23:15





















7














You can use function is.na<- in a lapply loop.



ret_list <- lapply(my_list, `is.na<-`)
ret_list
#$A
# a b c
#NA NA NA
#
#$B
# x y
#NA NA





share|improve this answer





























    4














    another alternative with dplyr:



    lapply(my_list, function(x) dplyr::na_if(x,x))





    share|improve this answer





























      4














      If the list is not restricted to one level then use rapply.



      # test data modified from question
      my_list2 <- list(list(A = c(a = 1, b = 2, c = 3)), B = c(x = 10, y = 20))

      rapply(my_list2, function(x) replace(x, TRUE, NA), how = "list")


      which can also be written as:



      rapply(my_list2, replace, list = TRUE, values = NA, how = "list")





      share|improve this answer





























        3














        Another way around



        relist(replace( unlist(my_list), TRUE, NA ), skeleton = my_list)

        #$A
        # a b c
        #NA NA NA

        #$B
        # x y
        #NA NA





        share|improve this answer





















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          5 Answers
          5






          active

          oldest

          votes








          5 Answers
          5






          active

          oldest

          votes









          active

          oldest

          votes






          active

          oldest

          votes









          8














          Here's another one for numeric vectors:



          lapply(my_list, `*`, NA) # Instead of * it could also be +, -, etc.
          # $A
          # a b c
          # NA NA NA
          #
          # $B
          # x y
          # NA NA


          More generally,



          lapply(my_list, replace, TRUE, NA)


          and



          lapply(ret_list, ifelse, NA, NA)





          share|improve this answer























          • what is * called as in this context ?
            – YOLO
            Dec 31 '18 at 23:12






          • 1




            @YOLO, I'm not sure what you mean. The first approach is the same as lapply(my_list, function(x) x * NA), so * is the usual product, which results to NA when one of the factors is NA.
            – Julius Vainora
            Dec 31 '18 at 23:15


















          8














          Here's another one for numeric vectors:



          lapply(my_list, `*`, NA) # Instead of * it could also be +, -, etc.
          # $A
          # a b c
          # NA NA NA
          #
          # $B
          # x y
          # NA NA


          More generally,



          lapply(my_list, replace, TRUE, NA)


          and



          lapply(ret_list, ifelse, NA, NA)





          share|improve this answer























          • what is * called as in this context ?
            – YOLO
            Dec 31 '18 at 23:12






          • 1




            @YOLO, I'm not sure what you mean. The first approach is the same as lapply(my_list, function(x) x * NA), so * is the usual product, which results to NA when one of the factors is NA.
            – Julius Vainora
            Dec 31 '18 at 23:15
















          8












          8








          8






          Here's another one for numeric vectors:



          lapply(my_list, `*`, NA) # Instead of * it could also be +, -, etc.
          # $A
          # a b c
          # NA NA NA
          #
          # $B
          # x y
          # NA NA


          More generally,



          lapply(my_list, replace, TRUE, NA)


          and



          lapply(ret_list, ifelse, NA, NA)





          share|improve this answer














          Here's another one for numeric vectors:



          lapply(my_list, `*`, NA) # Instead of * it could also be +, -, etc.
          # $A
          # a b c
          # NA NA NA
          #
          # $B
          # x y
          # NA NA


          More generally,



          lapply(my_list, replace, TRUE, NA)


          and



          lapply(ret_list, ifelse, NA, NA)






          share|improve this answer














          share|improve this answer



          share|improve this answer








          edited 2 days ago

























          answered Dec 31 '18 at 22:58









          Julius Vainora

          32.7k75979




          32.7k75979












          • what is * called as in this context ?
            – YOLO
            Dec 31 '18 at 23:12






          • 1




            @YOLO, I'm not sure what you mean. The first approach is the same as lapply(my_list, function(x) x * NA), so * is the usual product, which results to NA when one of the factors is NA.
            – Julius Vainora
            Dec 31 '18 at 23:15




















          • what is * called as in this context ?
            – YOLO
            Dec 31 '18 at 23:12






          • 1




            @YOLO, I'm not sure what you mean. The first approach is the same as lapply(my_list, function(x) x * NA), so * is the usual product, which results to NA when one of the factors is NA.
            – Julius Vainora
            Dec 31 '18 at 23:15


















          what is * called as in this context ?
          – YOLO
          Dec 31 '18 at 23:12




          what is * called as in this context ?
          – YOLO
          Dec 31 '18 at 23:12




          1




          1




          @YOLO, I'm not sure what you mean. The first approach is the same as lapply(my_list, function(x) x * NA), so * is the usual product, which results to NA when one of the factors is NA.
          – Julius Vainora
          Dec 31 '18 at 23:15






          @YOLO, I'm not sure what you mean. The first approach is the same as lapply(my_list, function(x) x * NA), so * is the usual product, which results to NA when one of the factors is NA.
          – Julius Vainora
          Dec 31 '18 at 23:15















          7














          You can use function is.na<- in a lapply loop.



          ret_list <- lapply(my_list, `is.na<-`)
          ret_list
          #$A
          # a b c
          #NA NA NA
          #
          #$B
          # x y
          #NA NA





          share|improve this answer


























            7














            You can use function is.na<- in a lapply loop.



            ret_list <- lapply(my_list, `is.na<-`)
            ret_list
            #$A
            # a b c
            #NA NA NA
            #
            #$B
            # x y
            #NA NA





            share|improve this answer
























              7












              7








              7






              You can use function is.na<- in a lapply loop.



              ret_list <- lapply(my_list, `is.na<-`)
              ret_list
              #$A
              # a b c
              #NA NA NA
              #
              #$B
              # x y
              #NA NA





              share|improve this answer












              You can use function is.na<- in a lapply loop.



              ret_list <- lapply(my_list, `is.na<-`)
              ret_list
              #$A
              # a b c
              #NA NA NA
              #
              #$B
              # x y
              #NA NA






              share|improve this answer












              share|improve this answer



              share|improve this answer










              answered Dec 31 '18 at 23:16









              Rui Barradas

              16.1k41730




              16.1k41730























                  4














                  another alternative with dplyr:



                  lapply(my_list, function(x) dplyr::na_if(x,x))





                  share|improve this answer


























                    4














                    another alternative with dplyr:



                    lapply(my_list, function(x) dplyr::na_if(x,x))





                    share|improve this answer
























                      4












                      4








                      4






                      another alternative with dplyr:



                      lapply(my_list, function(x) dplyr::na_if(x,x))





                      share|improve this answer












                      another alternative with dplyr:



                      lapply(my_list, function(x) dplyr::na_if(x,x))






                      share|improve this answer












                      share|improve this answer



                      share|improve this answer










                      answered Dec 31 '18 at 23:36









                      Mankind_008

                      1,4762312




                      1,4762312























                          4














                          If the list is not restricted to one level then use rapply.



                          # test data modified from question
                          my_list2 <- list(list(A = c(a = 1, b = 2, c = 3)), B = c(x = 10, y = 20))

                          rapply(my_list2, function(x) replace(x, TRUE, NA), how = "list")


                          which can also be written as:



                          rapply(my_list2, replace, list = TRUE, values = NA, how = "list")





                          share|improve this answer


























                            4














                            If the list is not restricted to one level then use rapply.



                            # test data modified from question
                            my_list2 <- list(list(A = c(a = 1, b = 2, c = 3)), B = c(x = 10, y = 20))

                            rapply(my_list2, function(x) replace(x, TRUE, NA), how = "list")


                            which can also be written as:



                            rapply(my_list2, replace, list = TRUE, values = NA, how = "list")





                            share|improve this answer
























                              4












                              4








                              4






                              If the list is not restricted to one level then use rapply.



                              # test data modified from question
                              my_list2 <- list(list(A = c(a = 1, b = 2, c = 3)), B = c(x = 10, y = 20))

                              rapply(my_list2, function(x) replace(x, TRUE, NA), how = "list")


                              which can also be written as:



                              rapply(my_list2, replace, list = TRUE, values = NA, how = "list")





                              share|improve this answer












                              If the list is not restricted to one level then use rapply.



                              # test data modified from question
                              my_list2 <- list(list(A = c(a = 1, b = 2, c = 3)), B = c(x = 10, y = 20))

                              rapply(my_list2, function(x) replace(x, TRUE, NA), how = "list")


                              which can also be written as:



                              rapply(my_list2, replace, list = TRUE, values = NA, how = "list")






                              share|improve this answer












                              share|improve this answer



                              share|improve this answer










                              answered Jan 1 at 0:10









                              G. Grothendieck

                              145k9126231




                              145k9126231























                                  3














                                  Another way around



                                  relist(replace( unlist(my_list), TRUE, NA ), skeleton = my_list)

                                  #$A
                                  # a b c
                                  #NA NA NA

                                  #$B
                                  # x y
                                  #NA NA





                                  share|improve this answer


























                                    3














                                    Another way around



                                    relist(replace( unlist(my_list), TRUE, NA ), skeleton = my_list)

                                    #$A
                                    # a b c
                                    #NA NA NA

                                    #$B
                                    # x y
                                    #NA NA





                                    share|improve this answer
























                                      3












                                      3








                                      3






                                      Another way around



                                      relist(replace( unlist(my_list), TRUE, NA ), skeleton = my_list)

                                      #$A
                                      # a b c
                                      #NA NA NA

                                      #$B
                                      # x y
                                      #NA NA





                                      share|improve this answer












                                      Another way around



                                      relist(replace( unlist(my_list), TRUE, NA ), skeleton = my_list)

                                      #$A
                                      # a b c
                                      #NA NA NA

                                      #$B
                                      # x y
                                      #NA NA






                                      share|improve this answer












                                      share|improve this answer



                                      share|improve this answer










                                      answered Dec 31 '18 at 23:30









                                      989

                                      8,91251834




                                      8,91251834






























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